Many companies in high technology fields engage with alliance partners to reduce risks, create synergies and learn. While the challenges of managing individual alliances are well documented, little is known on how to manage several R&D alliances simultaneously. Multiple alliance strategies can be observed in several companies engaged in the cross section of telecommunication and mobile technology where increased complexity magnifies managerial challenges. Drawing on modern portfolio theory, this paper offers a model for managing portfolios of R&D alliances. In particular, an analysis of a technology platform leader reveals how companies can reduce several types of risks associated with new technology and gain synergies by engaging in several alliances simultaneously.